Casting for Motor and Gearbox with Integrated Inverter

ABSTRACT

A powertrain for an electric vehicle includes a casting that houses an electric motor, an inverter, and a gearbox. The inverter, which is coupled to the electric motor, converts direct current from a battery to alternating current for the electric motor. The gearbox is connected to the electric motor. The electric motor includes a stator and a rotor with a rotor shaft that extends beyond the stator. The inverter may be situated on an opposite side of the rotor shaft from an axle to which the gearbox is coupled.

RELATED APPLICATION

This application claims priority and benefit to U.S. ProvisionalApplication No. 62/624,676, filed Jan. 31, 2018, entitled “Casting forMotor and Gearbox with Integrated Inverter,” which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD

This relates generally to powertrains for electric vehicles, includingbut not limited to powertrains in which the inverter is housed in thecasting that houses the motor and gearbox.

BACKGROUND

The powertrain of an electric vehicle includes a battery, an inverter, amotor, and a gearbox. The inverter is typically situated in a housingseparate from the housing for the motor and gearbox. This separatehousing adds to the size and weight of the powertrain and is problematicwith regard to noise, vibration, and harshness (NVH).

SUMMARY

In some implementations, a powertrain includes a casting that houses anelectric motor, an inverter, and a gearbox. The inverter, which iscoupled to the electric motor, converts direct current from a battery toalternating current for the electric motor. The gearbox is connected tothe electric motor. The size of the drive unit is thus reduced, as arethe number of parts and weight of the powertrain. The integration of theinverter inside the casting also may allow the stiffness of the castingto be increased, thereby mitigating NVH.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the various described implementations,reference should be made to the Detailed Description below, inconjunction with the following drawings in which like reference numeralsrefer to corresponding parts throughout the figures.

FIG. 1A is a schematic diagram illustrating components of an inverter inaccordance with some implementations.

FIG. 1B is a schematic diagram illustrating components of a three-phaseinverter in accordance with some implementations.

FIG. 2 is a perspective diagram illustrating components of a three-phaseinverter in accordance with some implementations.

FIGS. 3A-3B are perspective diagrams illustrating components of thethree-phase inverter of FIG. 2 in accordance with some implementations.

FIG. 4 illustrates a side-view of the three-phase inverter of FIG. 2 inaccordance with some implementations.

FIG. 5 illustrates a cross-sectional view of an inverter (e.g., thethree-phase inverter of FIG. 2) in accordance with some implementations.

FIG. 6 is a perspective diagram illustrating components of an inverter(e.g., the three-phase inverter of FIG. 2) with encased components inaccordance with some implementations.

FIG. 7 is a perspective diagram illustrating components of a three-phaseinverter (e.g., the three-phase inverter of FIG. 2) with an associatedcircuit board in accordance with some implementations.

FIG. 8 is a perspective diagram illustrating components of a three-phaseinverter in accordance with some implementations.

FIG. 9 is a cut-away perspective diagram illustrating components of thethree-phase inverter of FIG. 8 in accordance with some implementations.

FIG. 10 illustrates a side-view of the three-phase inverter of FIG. 8 inaccordance with some implementations.

FIG. 11 is a perspective diagram illustrating components of thethree-phase inverter of FIG. 8 in accordance with some implementations.

FIG. 12 is a bottom-view perspective diagram illustrating components ofthe three-phase inverter of FIG. 8 in accordance with someimplementations.

FIG. 13 is a bottom-view perspective diagram illustrating components ofthe three-phase inverter of FIG. 8 in accordance with someimplementations.

FIGS. 14-16 are respective side views of a casting in accordance withsome implementations.

FIG. 17 is a cross-sectional view showing components within the castingof FIGS. 14-16 in accordance with some implementations.

FIGS. 18A and 18B are respective side and perspective views ofcomponents within the casting of FIGS. 14-16 situated at their positionswithin the casting, but with the casting omitted for visual clarity, inaccordance with some implementations

Like reference numerals refer to corresponding parts throughout thedrawings and specification. Like fill patterns indicate correspondingparts throughout the drawings.

DETAILED DESCRIPTION

Reference will now be made in detail to implementations, examples ofwhich are illustrated in the accompanying drawings. In the followingdetailed description, numerous specific details are set forth in orderto provide a thorough understanding of the various describedimplementations. However, it will be apparent to one of ordinary skillin the art that the various described implementations may be practicedwithout these specific details. In other instances, well-known methods,procedures, components, circuits, and networks have not been describedin detail so as not to unnecessarily obscure aspects of theimplementations.

Many modifications and variations of this disclosure can be made withoutdeparting from its spirit and scope, as will be apparent to thoseskilled in the art. The specific implementations described herein areoffered by way of example only, and the disclosure is to be limited onlyby the terms of the appended claims, along with the full scope ofequivalents to which such claims are entitled.

FIG. 1A is a schematic diagram illustrating components of an inverter100 in accordance with some implementations. The inverter 100 includes acapacitor 102 electrically coupled to transistors 104 and 106 viapositive rail 105 and negative rail 107. The positive rail 105 andnegative rail 107 may be implemented as respective bus bars. Thepositive rail 105 and transistor 104 are electrically coupled to apositive terminal of the capacitor 102, while the negative rail 107 andtransistor 106 are electrically coupled to a negative terminal of thecapacitor 102. The negative rail 107 is further coupled to a negativeterminal of a battery 108 and the positive rail is further coupled to apositive terminal of the battery 108. In accordance with someimplementations, direct current (DC) from the battery 108 is convertedby the inverter 100 to alternating current (AC) and provided to a motor110. A phase-out bus bar 109, which connects the transistors 104 and106, provides the AC to the motor 110.

In various implementations, the capacitor 102 is a wound film capacitor,ceramic capacitor, or electrolytic capacitor. In some implementations,the capacitor 102 is composed of a plurality of energy-storagecomponents (i.e., capacitor components) coupled to one another inparallel.

In some implementations (e.g., as shown in FIG. 1A), the transistors 104and 106 are bipolar transistors, such as insulated-gate bipolartransistors (IGBTs) that each include a gate terminal (“G”), a collectorterminal (“C”), and an emitter terminal (“E”). In other implementations,one or more (e.g., all) of the transistors 104 and 106 are field-effecttransistors (FETs), such as metal-oxide semiconductor field-effecttransistors (MOSFETs) (e.g., silicon carbide (SiC) MOSFETs) orgallium-nitride (GaN) FETs, that each include a gate terminal and twosource/drain terminals.

As shown in FIG. 1A, the collector terminal of the transistor 104 iscoupled to the positive terminal of the capacitor 102 via the positiverail 105. The emitter terminal of the transistor 104 is coupled to thecollector terminal of the transistor 106 via the phase-out bus bar 109.The emitter terminal of the transistor 106 is coupled to the capacitor102 via negative rail 107.

The gate terminal of the transistor 104 is coupled to a driver 112 andthe gate terminal of the transistor 106 is coupled to a driver 114. Insome implementations, the drivers 112 and 114 comprise driver circuitry(e.g., respective integrated circuits) on a printed circuit board (PCB),such as board 702 in FIG. 7. The drivers 112 and 114 switch thetransistors 104 and 106 on and off in an alternating manner, thusalternatingly coupling the phase-out bus bar 109 to the positive rail105 and negative rail 107, to produce AC on the phase-out bus bar.

FIG. 1B is a schematic diagram illustrating a three-phase inverter 115in accordance with some implementations. The inverter 115 includes acapacitor 102 coupled to a three-phase switch 122 via the positive rail105 and negative rail 107. An inductor 120 on positive rail 105represents commutating inductance between the rails and phase-out busbars. This inductance 120, which is a parasitic inductance, is reduced(e.g., minimized) by reducing area between the rails 105 and 107 and thephase-out bus bars (e.g., as shown in FIG. 5). (A commutating inductanceis also present in the inverter 100 but is not shown in FIG. 1A forsimplicity.)

The three-phase switch 122 includes transistors 124 (124-1, 124-2, and124-3) coupled to the capacitor 102 via the positive rail 105 andtransistors 126 (126-1, 126-2, and 126-3) coupled to the capacitor 102via the negative rail 107. Pairs of transistors 124-1 and 126-1, 124-2and 126-2, and 124-3 and 126-3 are each coupled in series between thepositive rail 105 and negative rail 107. In some implementations, thetransistors 124 are coupled to the positive rail 105 via respectivecollector terminals, and the transistors 126 are coupled to the negativerail 107 via respective emitter terminals (e.g., the transistors 124 and126 are IGBTs). In some implementations, the transistors 124 and 126 areFETs (e.g., SiC MOSFETs or GaN FETs); the transistors 124 are coupled tothe positive rail 105 via respective source/drain terminals and thetransistors 126 are coupled to the negative rail 107 via respectivesource/drain terminals. The inverter 115 further includes threephase-out bus bars, denoted P_(A), P_(B), and P_(C), which are coupledbetween respective terminals of respective pairs of the transistors 124and 126. For example, P_(A), P_(B), and P_(C) are coupled to therespective emitter terminals of transistors 124 and collector terminalsof transistors 126: P_(A) is coupled to the emitter terminal oftransistor 124-1 and to the collector terminal of transistor 126-1,P_(B) is coupled to the emitter terminal of transistor 124-2 and to thecollector terminal of transistor 126-2, and P_(C) is coupled to theemitter terminal of transistor 124-3 and to the collector terminal oftransistor 126-3. The transistors are driven by drivers (e.g., drivers112 and 114, FIG. 1A). The timing of the drivers is varied between thepairs of transistors 124 and 126, such that each phase-out bus barP_(A), P_(B), and P_(C) provides a distinct phase of AC. In someimplementations, the phase-out bus bars are coupled to a motor, such asthe motor 110 (FIG. 1A).

FIGS. 2, 3A-3B, 4, and 5 illustrate various views of a three-phaseinverter 200, which is an example of the three-phase inverter 115 (FIG.1B), in accordance with some implementations. FIG. 2 shows capacitorcomponents 102-1 and 102-2 coupled to transistors 202 (e.g., 202-1through 202-5), 204 (e.g., 204-1 through 204-5), 206 (e.g., 206-1through 206-5) via negative rail 107 and coupled to transistors 210(e.g., 210-1 through 210-5), 212 (e.g., 212-1 through 212-5), and 214(e.g., 214-1 through 214-5) via positive rail 105. The negative rail 107and positive rail 105 are implemented as respective bus bars. Thetransistors 202 are coupled to the transistors 214 via a phase-out busbar 109-1, the transistors 204 are coupled to the transistors 212 via aphase-out bus bar 109-2, and the transistors 206 are coupled to thetransistors 210 via a phase-out bus bar 109-3.

The transistors 202-1 through 202-5 are thus arranged in parallelbetween the negative rail/bus bar 107 and the phase-out bus bar 109-1.The transistors 204-1 through 204-5 are thus arranged in parallelbetween the negative rail/bus bar 107 and the phase-out bus bar 109-2.The transistors 206-1 through 206-5 are thus arranged in parallelbetween the negative rail/bus bar 107 and the phase-out bus bar 109-3.The transistors 210-1 through 210-5 are thus arranged in parallelbetween the positive rail/bus bar 105 and the phase-out bus bar 109-3.The transistors 212-1 through 212-5 are thus arranged in parallelbetween the positive rail/bus bar 105 and the phase-out bus bar 109-2.And the transistors 214-1 through 214-5 are thus arranged in parallelbetween the positive rail/bus bar 105 and the phase-out bus bar 109-1.

In some implementations, the transistors 202, 204, 206, 210, 212, and/or214 are bipolar transistors (e.g., IGBTs). Alternatively, thetransistors 202, 204, 206, 210, 212, and/or 214 are FETs (e.g., SiCMOSFETs or GaN FETs). The transistors 202, 204, and 206 each includethree leads, with a first lead (e.g., corresponding to an emitterterminal or source/drain terminal of the transistor) coupled to thenegative rail/bus bar 107 and a second lead (e.g., corresponding to acollector terminal or source/drain terminal of the transistor) coupledto a corresponding phase-out bus bar 109. The transistors 210, 212, and214 each include three leads, with a first lead (e.g., corresponding toa collector terminal of the transistor) coupled to the positive rail/busbar 105 and a second lead (e.g., corresponding to an emitter terminal ofthe transistor) coupled to a corresponding phase-out bus bar 109. Forexample, FIG. 5 shows the transistor 202-1 having a collector lead502-1, an emitter lead 504-1, and a gate lead 506-1 and transistor 214-1having a collector lead 502-2, an emitter lead 504-2, and a gate lead506-2. The collector lead 502-1 of transistor 202-1 is coupled to theemitter lead 504-2 of transistor 214-1 via the phase-out bus bar 109-1(e.g., by soldering or welding the collector lead 502-1 and emitter lead504-2 to the phase-out bus bar 109-1), the emitter lead 504-1 oftransistor 202-1 is coupled to the negative rail/bus bar 107 (e.g.,soldered or welded to the negative rail/bus bar 107), and the collectorlead 502-2 of transistor 214-1 is coupled to the positive rail/bus bar105 (e.g., soldered or welded to the positive rail/bus bar 105).

In some implementations, the third lead of each transistor 202, 204, and206 (e.g., corresponding to a gate terminal of the transistor) iscoupled to driver circuitry (not shown) (e.g., drivers 114, FIG. 1A). Insome implementations, the third lead of each transistor 210, 212, and214 (e.g., corresponding to a gate terminal of the transistor) iscoupled to driver circuitry (not shown) (e.g., drivers 112, FIG. 1A).

The positive rail/bus bar 105 and the negative rail/bus bar 107 eachinclude a respective battery-coupling portion 216 for coupling to abattery, such as the battery 108 (FIG. 1B). The phase-out bus bars 109-1through 109-3 each include a respective motor-coupling portion 302-1through 302-3 (FIG. 3B) for coupling the phase-out bus bars 109 to amotor (e.g., motor 110, FIG. 1A), in accordance with someimplementations.

In some implementations, the capacitor 102 has a positive terminal(e.g., at a first end) (e.g., on the bottom, or alternatively on thetop, of the capacitor 102) and a negative terminal (e.g., at a secondend opposite of the first end) (e.g., on the top, or alternatively thebottom, of the capacitor 102). The capacitor 102 comprises multiplecapacitor components (e.g., capacitor components 102-1 through 102-6 andother capacitor components that are not visible in the drawings due toperspective) in accordance with some implementations.

As shown in FIG. 5, the positive rail/bus bar 105 is coupled to a firstside (e.g., the bottom), and thus to a positive terminal, of thecapacitor 102 and the negative rail/bus bar 107 is coupled to a secondside (e.g., the top), and thus to a negative terminal, of the capacitor102. In some implementations, the phase-out bus bars 109 overlay thenegative rail/bus bar 107 so as to minimize an area between thephase-out bus bars 109 and the negative rail/bus bar 107. The rail/busbars 105 and 107 and the phase-out bus bars 109 are composed of anelectrically-conductive material. For example, the rails/bus bars 105and 107 and the phase-out bus bars 109 are composed of metal (e.g.,copper).

In some implementations, the areas between the rail/bus bars and thephase-out bus bars 109 shown in FIG. 5 (e.g., the area between thenegative rail/bus bar 107 and the phase-out bus bar 109-1) are filledwith an insulating material (e.g., a thermally and/or electricallyinsulating material). For example, one or more (e.g., all) of the areasare filled with an epoxy.

Although the figures show the positive rail/bus bar 105 coupled to aside of the capacitor opposite of the phase-out bus bars 109 andtransistors, in some implementations, the relative positioning of thepositive rail/bus bar 105 and the negative rail/bus bar 107 is reversed,such that the positive rail/bus bar 105 is coupled to a side of thecapacitor closest to the phase-out bus bars 109 and the transistors (notshown).

Although the figures show sets of five parallel transistors (e.g.,transistors 202-1 through 202-5 and transistors 214-1 through 214-5), insome implementations, a different number of transistors are used (e.g.,3, 4, or 6 transistors) for each set of parallel transistors. In someimplementations, the inverter is configured to operate with varyingnumbers of transistors for different phases. For example, the inverteris configured to utilize two sets of three transistors for a first phase(e.g., corresponding to phase-out bus bar 109-1), utilize two sets offour transistors for a second phase (e.g., corresponding to phase-outbus bar 109-2), and utilize two sets of six transistors for a thirdphase (e.g., corresponding to phase-out bus bar 109-3). In someimplementations, the inverter is configured to utilize transistors ofvarying size and performance.

FIG. 6 is a perspective diagram illustrating components of an inverter600 with encased components in accordance with some implementations. Thecapacitor 102 and portions of the positive rail/bus bar 105, negativerail/bus bar 107, and phase-out bus bars 109 are encased in a case 602such that coupling portions of the positive rail/bus bar 105, thenegative rail/bus bar 107, and the phase-out bus bars 109 extend fromthe case 602. The coupling portions of the positive rail/bus bar 105include positive couplings 604 (e.g., 604-1 through 604-5) to contact afirst set of transistors (e.g., the transistors 214 in FIG. 2). Thecoupling portions of the negative rail/bus bar 107 include negativecouplings 608 (e.g., 608-1 through 608-5) to contact a second set oftransistors (e.g., the transistors 202 in FIG. 2). The coupling portionsof the phase-out bus bars 109 include phase-out couplings 606 (e.g.,606-1 through 606-5 for phase-out bus bar 109-1) to contact the firstset of transistors, and phase-out couplings 610 (e.g., 610-1 through610-5 for phase-out bus bar 109-1) to contact the second set oftransistors. In some implementations, battery-coupling portions of thepositive rail/bus bar 105 and the negative rail/bus bar 107 (e.g.,battery-coupling portions 216) extend from the case 602. In someimplementations, motor-coupling portions of the phase-out bus bars 109(e.g., motor-coupling portions 302) extend from the case 602.

In accordance with some implementations, the capacitor 102 and portionsof the positive rail/bus bar 105, negative rail/bus bar 107, andphase-out bus bars 109 are enclosed in the case 602 with a sealant 604,such as epoxy. In some implementations, the case 602 is composed of aplastic or polymer. In some implementations, the case 602 is adapted toprovide structural support for the inverter 600. In someimplementations, the case 602 and sealant 604 are adapted to preventmoisture from contacting the capacitor 102.

Although the coupling portions shown in FIG. 6 are flag-shaped, invarious implementations, the coupling portions have other geometric(e.g., rectangular) or non-geometric shapes.

In accordance with some implementations, during assembly of theinverter, the rails/bus bars 105 and 107 and phase-out bus bars 109 arefirst mechanically coupled with the capacitor 102 to provide a capacitorassembly. The capacitor assembly is then placed in the case 602 and thesealant 604 is applied to seal the capacitor assembly within the case602. After sealing the case 602, the transistors 202, 204, 206, 210,212, and 214 are coupled to respective coupling portions 604 of thepositive rail/bus bar 105, coupling portions 606 and 610 of thephase-out bus bars 109, and coupling portions 608 of the negativerail/bus bar 107.

FIG. 7 is a perspective diagram illustrating components of a three-phaseinverter 700 in accordance with some implementations. FIG. 7 shows theinverter 200 coupled to a board 702. In some implementations, the board702 comprises a printed circuit board (PCB). In some implementations,the board 702 includes circuitry, such as driver circuitry (not shown),for controlling switching of the transistors 202, 204, 206, 210, 212,and 214. In some implementations, the drivers 112 and 114 (FIG. 1A) arelocated on the board 702 (e.g., for each of the three phases). In someimplementations, the board 702 includes distinct driver circuitry foreach set of transistors 202, 204, 206, 210, 212, and 214. While the case602 is not shown in FIG. 7, in practice the inverter 700 includes thecase 602 (e.g., is an example of the inverter 600, FIG. 6).

In FIGS. 2-7, the transistors 202, 204, 206, 210, 212, and 214 arelocated above and to the sides of the case 602 (and thus above and tothe sides of the capacitor 102) in a wing-like configuration.Alternatively, the transistors 202, 204, 206, 210, 212, and 214 may besituated in-line with the case 602 (and thus in-line with the capacitor102). FIGS. 8-13 illustrate an inverter 800 with such a configuration:the transistors 202, 204, 206, 210, 212, and 214 are located between thecapacitor 102 and an underlying heat-sink casing 804, in accordance withsome embodiments. The heat-sink casing 804 is shown in FIGS. 8-10 and13, with FIG. 10 providing a side view and FIG. 13 providing a bottomperspective view. Electrically, the inverter 800 (FIGS. 8-13) isschematically equivalent to the inverter 200 (FIGS. 2-7).

The heat-sink casing 804 includes one or more heat sinks 810 (FIG. 9)for the transistors 202, 204, 206, 210, 212, and 214. In someembodiments, each transistor includes an exposed metallic lead-frame 814(FIG. 12, which is a bottom perspective view of the inverter with theheat-sink casing 804 omitted to reveal the transistors) The metalliclead-frame 814 (e.g., a copper slug) is exposed through the transistor'spackaging and is connected to the heat-sink casing 804, and thus to theheat sinks 810. The connection between the metallic lead-frames 814 andthe heat sinks 810 dissipates heat from the transistors. The heat-sinkcasing 804 has an internal channel through which fluid flows todissipate heat from the heat sinks 810 and thus from the transistors.The fluid enters the channel through a fluid connection 806 at a firstend of the heat-sink casing 804, flows around the heat sinks 810, andexits the channel through a fluid connection 806 at a second end of theheat-sink casing 804. The heat-sink casing 804 also includes mountingbosses 808 (e.g., threaded bosses). For example, the mounting bosses 808connect the heat-sink casing 804 to a supporting structure (e.g., in theelectric vehicle powered by the inverter), an associated case (distinctfrom the case 602), and/or an associated printed circuit board (e.g.,with drivers 112 and 114, FIG. 1A). (The heat-sink casing 804 is omittedfrom FIG. 11 as well as FIG. 12, for visual clarity.)

The case 602 is not shown in FIGS. 8-13 for visual clarity, so thatcomponents within the case 602 may be seen. In the example of FIGS.8-13, the case 602 is situated upside-down in comparison to theconfiguration of FIG. 6, such that the top side of the case 602 facesthe transistors 202, 204, 206, 210, 212, and 214 and the bottom side ofthe case 602 faces upward (in the orientation of FIGS. 8-13). Componentsin the case 602 include the capacitor 102 (e.g., capacitor components102-1, 102-2, etc.) and respective portions (e.g., conductive sheets) ofthe positive rail/bus bar 105, negative rail/bus bar 107, and phase-outbus bars 109-1, 109-2, and 109-3. Portions of the positive rail/bus bar105, negative rail/bus bar 107, and phase-out bus bars 109-1, 109-2, and109-3 extend from the top side of the case 602 to contact respectiveleads of the transistors 202, 204, 206, 210, 212, and 214. The case 602may be sealed with sealant 604.

Each phase-out bus bar 109-1, 109-2, and 109-3 includes a respectivemotor-coupling portion 802-1, 802-2, and 802-3 to provide a respectivephase of AC current to the motor (e.g., motor 110, FIGS. 1A-1B). Themotor-coupling portions 802-1, 802-2, and 802-3 are formed by portionsof the phase-out bus bars 109-1, 109-2, and 109-3 that extend from thecase 602. In some embodiments, the motor-coupling portions 802-1, 802-2,and 802-3 are implemented as angle brackets with apertures forconnecting the motor-coupling portions 802-1, 802-2, and 802-3 to leadsfor the motor. A battery coupling 812 (FIGS. 11-12) includes two prongs,respectively connected to the positive rail/bus bar 105 and the negativerail/bus bar 107, to connect to the battery (e.g., battery 108, FIGS.1A-1B). The prongs connect to respective portions of the positiverail/bus bar 105 and the negative rail/bus bar 107 that extend from thecase 602.

The inverter 800, with the transistors 202, 204, 206, 210, 212, and 214in-line between the capacitor 102 and heat-sink casing 804, has acompact arrangement that integrates efficiently with the rest of thedrive unit in an electric vehicle. This compact arrangement increasesthe inverter's volumetric power density.

In light of FIGS. 1-13, certain implementations are now described.

In accordance with some implementations, an inverter includes: (1) acase (e.g., the case 602); (2) a capacitor situated in the case (e.g.,the capacitor 102), the capacitor having a first terminal and a secondterminal; (3) a first transistor external to the case (e.g., thetransistor 214-1, or alternatively the transistor 202-1) and coupled tothe first terminal of the capacitor; (4) a second transistor external tothe case (e.g., the transistor 202-1, or alternatively the transistor214-1) and coupled between the first transistor and the second terminalof the capacitor; (5) a first bus bar (e.g., the positive rail/bus bar105, or alternatively the negative rail/bus bar 107) to connect thefirst terminal of the capacitor to the first transistor, the first busbar comprising a first portion situated in the case and a second portionextending from the case to contact the first transistor (e.g., thepositive coupling 604-1, or alternatively the negative coupling 608-1);(6) a second bus bar (e.g., the negative rail/bus bar 107, oralternatively the positive rail/bus bar 105) to connect the secondterminal of the capacitor to the second transistor, the second bus barcomprising a first portion situated in the case and a second portionextending from the case to contact the second transistor (e.g., thenegative coupling 608-1, or alternatively the positive coupling 604-1);and (7) a phase-out bus bar (e.g., the phase-out bus bar 109-1) toconnect the first transistor to the second transistor, the phase-out busbar comprising a first portion situated in the case, a second portionextending from the case to contact the first transistor (e.g., thephase-out coupling 606-1, or alternatively the phase-out coupling610-1), and a third portion extending from the case to contact thesecond transistor (e.g., the phase-out coupling 610-1, or alternativelythe phase-out coupling 606-1).

In some implementations, the first portion of the phase-out bus barcomprises a conductive sheet (e.g., composed of metal) situated abovethe capacitor in the case. For example, FIGS. 2, 5, and 10 show eachphase-out bus bar 109 having a portion comprising a conductive sheetsituated above the capacitor 102. (In FIG. 10, the phase-out bus bars109 are considered to be above the capacitor 102 because the capacitor102 is upside-down with respect to FIGS. 2 and 5.) In someimplementations, the first portion of the phase-out bus bar comprises aconductive sheet situated below, or to a side of, the capacitor in thecase.

In some implementations: (1) the first terminal of the capacitor is onthe bottom of the capacitor; (2) the first portion of the first bus barcomprises a conductive sheet situated below the capacitor in the case;(3) the second terminal of the capacitor is on the top of the capacitor;and (4) the first portion of the second bus bar comprises a conductivesheet situated above the capacitor and below the first portion of thephase-out bus bar in the case. For example, FIGS. 4, 5, and 8-11 showthe positive rail/bus bar 105 coupled to a bottom of the capacitor 102and comprising a conductive sheet situated below the capacitor. FIGS. 4,5, and 8-11 also show the negative rail/bus bar 107 coupled to a top ofthe capacitor 102 and comprising a conductive sheet that is situatedabove the capacitor and below a conductive sheet that is a portion ofthe phase-out bus bar 109-1. (In FIGS. 8-11, the conductive sheet ofnegative rail/bus bar 107 is considered to be below the conductive sheetthat is a portion of the phase-out bus bar 109-1 because the capacitor102 is upside-down with respect to FIGS. 4 and 5.)

In some implementations, the first terminal of the capacitor is apositive terminal and the second terminal of the capacitor is a negativeterminal. For example, FIGS. 5 and 10 show the bottom terminal (e.g.,the first terminal) of the capacitor 102 coupled to the positiverail/bus bar 105 and the top terminal (e.g., the second terminal) of thecapacitor 102 coupled to the negative rail/bus bar 107.

In some implementations, the case is sealed. The capacitor and the firstportions of the first bus bar, second bus bar, and phase-out bus bar aresealed in the case. In some implementations, the case is sealed withepoxy. For example, FIG. 6 shows the case 602 sealed with sealant 604with the coupling portions of the positive rail/bus bar 105, negativerail/bus bar 107, and phase-out bus bar 109 extending outside of thesealed case 602 and the other portions of the positive rail/bus bar 105,negative rail/bus bar 107, and phase-out bus bar 109 sealed within thecase 602.

In some implementations: (1) the first and second transistors areinsulated-gate bipolar transistors, each comprising an emitter, acollector, and a gate; (2) the collector of the first transistor iscoupled to the first terminal of the capacitor via the first bus bar;(3) the emitter of the first transistor is coupled to the collector ofthe second transistor via the phase-out bus bar; and (4) the emitter ofthe second transistor is coupled to the second terminal of the capacitorvia the second bus bar. For example, FIG. 5 shows the collector lead502-2 of the transistor 214-1 coupled to the positive rail/bus bar 105,the collector lead 502-1 of the transistor 202-1 coupled to the emitterlead 504-2 of the transistor 214-1 via the phase-out bus bar 109-1, andthe emitter lead 504-1 of the transistor 202-1 coupled to the negativerail/bus bar 107.

In some implementations: (1) the first and second transistors aresilicon-carbide metal-oxide-semiconductor field-effect transistors (SiCMOSFETs) or gallium-nitride field-effect transistors (GaN FETs), eachcomprising a first source/drain terminal, a second source/drainterminal, and a gate; (2) the first source/drain terminal of the firsttransistor is coupled to the first terminal of the capacitor via thefirst bus bar; (3) the second source/drain terminal of the firsttransistor is coupled to the first source/drain terminal of the secondtransistor via the phase-out bus bar; and (4) the second source/drainterminal of the second transistor is coupled to the second terminal ofthe capacitor via the second bus bar.

In some implementations, the phase-out bus bar is a first phase-out busbar (e.g., the phase-out bus bar 109-1) to provide a first phase ofalternating current. The inverter further includes: (1) a thirdtransistor external to the case (e.g., the transistor 212-1, oralternatively the transistor 204-1) and coupled to the first terminal ofthe capacitor; (2) a fourth transistor external to the case (e.g., thetransistor 204-1, or alternatively the transistor 212-1) and coupledbetween the third transistor and the second terminal of the capacitor;and (3) a second phase-out bus bar (e.g., the phase-out bus bar 109-2),distinct from the second bus bar, to connect the third transistor to thefourth transistor and to provide a second phase of alternating current.The second phase-out bus bar comprises a first portion situated in thecase, a second portion extending from the case to contact the thirdtransistor, and a third portion extending from the case to contact thefourth transistor.

In some implementations, the inverter further includes: (1) a fifthtransistor external to the case (e.g., the transistor 210-1, oralternatively the transistor 206-1) and coupled to the first terminal ofthe capacitor; (2) a sixth transistor external to the case (e.g., thetransistor 206-1, or alternatively the transistor 210-1) and coupledbetween the fifth transistor and the second terminal of the capacitor;and (3) a third phase-out bus bar (e.g., the phase-out bus bar 109-3) toconnect the fifth transistor to the sixth transistor and to provide athird phase of alternating current. The third phase-out bus barcomprises a first portion situated in the case, a second portionextending from the case to contact the fifth transistor, and a thirdportion extending from the case to contact the sixth transistor.

In some implementations, the first portions of the first, second, andthird phase-out bus bars comprise respective first, second, and thirdconductive sheets situated above the capacitor in the case and arrangedin a line. For example, FIG. 2 shows the phase-out bus bars 109-1,109-2, and 109-3 each having a sheet portion situated above thecapacitor 102 and arranged in a line.

In some implementations: (1) the first terminal of the capacitor is onthe bottom of the capacitor; (2) the first portion of the first bus barcomprises a conductive sheet situated below the capacitor in the case;(3) the second terminal of the capacitor is on the top of the capacitor;and (4) the first portion of the second bus bar comprises a conductivesheet situated above the capacitor and below the first, second, andthird conductive sheets. For example, FIGS. 4, 5, and 8-11 show thepositive rail/bus bar 105 coupling to a bottom of the capacitor 102 andcomprising a conductive sheet below the capacitor 102, the negativerail/bus bar 107 coupling to a top of the capacitor 102 and comprising aconductive sheet above the capacitor 102, and the conductive sheets ofthe phase-out bus bars 109 situated above the conductive sheet of thenegative rail/bus bar 107. (Again, the capacitor 102 is upside down inFIGS. 8-11 as compared to FIGS. 4 and 5.)

In some implementations: (1) the first transistor is one of a firstplurality of transistors (e.g., the transistors 214-1 through 214-5, oralternatively the transistors 202-1 through 202-5) coupled to the firstterminal of the capacitor, the first plurality of transistors beingexternal to the case; (2) the second transistor is one of a secondplurality of transistors (e.g., the transistors 202-1 through 202-5, oralternatively the transistors 214-1 through 214-5) coupled between thefirst plurality of transistors and the second terminal of the capacitor,the second plurality of transistors being external to the case; (3) thefirst bus bar connects the first terminal of the capacitor to the firstplurality of transistors and comprises a plurality of portions (e.g.,the positive couplings 604-1 through 604-5, or alternatively thenegative couplings 608-1 through 608-5) extending from the case tocontact respective transistors of the first plurality of transistors;(4) the second bus bar connects the second terminal of the capacitor tothe second plurality of transistors and comprises a plurality ofportions (e.g., the negative couplings 608-1 through 608-5, oralternatively the positive couplings 604-1 through 604-5) extending fromthe case to contact respective transistors of the second plurality oftransistors; and (5) the phase-out bus bar connects the first pluralityof transistors to the second plurality of transistors and comprises afirst plurality of portions (e.g., the phase-out couplings 604-1 through604-5, or alternatively the phase-out couplings 610-1 through 610-5)extending from the case to contact respective transistors of the firstplurality of transistors and a second plurality of portions (e.g., thephase-out couplings 610-1 through 610-5, or alternatively the phase-outcouplings 604-1 through 604-5) extending from the case to contactrespective transistors of the second plurality of transistors.

In some implementations, each transistor of the first and secondpluralities of transistors is a discrete transistor with its ownpackage. For example, FIG. 2 shows each transistor 202 and eachtransistor 214 as discrete transistors with discrete packaging. Eachtransistor 204, 206, 210, and 210 may also be a discrete transistor withdiscrete packaging.

In some implementations, the phase-out bus-bar is a first phase-out busbar to provide a first phase of alternating current, and the inverterfurther includes: (1) a third plurality of transistors (e.g., thetransistors 212-1 through 212-5, or alternatively the transistors 204-1through 204-5) coupled to the first terminal of the capacitor, the thirdplurality of transistors being external to the case; (2) a fourthplurality of transistors (e.g., the transistors 204-1 through 204-5, oralternatively the transistors 212-1 through 212-5) coupled between thethird plurality of transistors and the second terminal of the capacitor,the fourth plurality of transistors being external to the case; (3) asecond phase-out bus bar (e.g., phase-out bus bar 109-2) to connect thethird plurality of transistors to the fourth plurality of transistorsand to provide a second phase of alternating current, the secondphase-out bus bar comprising a portion situated in the case and aplurality of portions extending from the case to contact respectivetransistors of the third and fourth pluralities of transistors; (4) afifth plurality of transistors (e.g., the transistors 210-1 through210-5, or alternatively the transistors 206-1 through 206-5) coupled tothe first terminal of the capacitor, the fifth plurality of transistorsbeing external to the case; (5) a sixth plurality of transistors (e.g.,the transistors 206-1 through 206-5, or alternatively the transistors210-1 through 210-5) coupled between the fifth plurality of transistorsand the second terminal of the capacitor, the sixth plurality oftransistors being external to the case; and (6) a third phase-out busbar (e.g., the phase-out bus bar 109-3) to connect the fifth pluralityof transistors to the sixth plurality of transistors and to provide athird phase of alternating current, the third phase-out bus barcomprising a portion situated in the case and a plurality of portionsextending from the case to contact respective transistors of the fifthand sixth pluralities of transistors. The first bus bar connects thefirst terminal of the capacitor to the third and fifth pluralities oftransistors and comprises a plurality of portions extending from thecase to contact respective transistors of the third and fifthpluralities of transistors. The second bus bar connects the secondterminal of the capacitor to the fourth and sixth pluralities oftransistors and comprises a plurality of portions extending from thecase to contact respective transistors of the fourth and sixthpluralities of transistors.

In accordance with some implementations, a three-phase inverterincludes: (1) a sealed case (e.g., the case 602); (2) a capacitor sealedin the case (e.g., the capacitor 102), the capacitor having a firstterminal and a second terminal; (3) first, second, third, fourth, fifthand sixth pluralities of transistors (e.g., the transistors 202, 204,206, 210, 212, and 214) external to the case, where: (a) the first,third, and fifth pluralities of transistors are coupled to the firstterminal of the capacitor (e.g., the transistors 214, 212, and 210, oralternatively the transistors 202, 204, and 206); and (b) the second,fourth, and sixth pluralities of transistors (e.g., the transistors 202,204, and 206, or alternatively the transistors 214, 212, and 210) arecoupled to the second terminal of the capacitor; (4) a first bus bar(e.g., the positive rail/bus bar 105, or alternatively the negativerail/bus bar 107) to connect the first terminal of the capacitor to thefirst, third, and fifth pluralities of transistors, the first bus barcomprising a first portion sealed in the case and respective portionsextending from the case to contact respective transistors of the first,third, and fifth pluralities of transistors; (5) a second bus bar (e.g.,the negative rail/bus bar 107, or alternatively the positive rail/busbar 105) to connect the second terminal of the capacitor to the second,fourth, and sixth pluralities of transistors, the second bus barcomprising a first portion sealed in the case and respective portionsextending from the case to contact respective transistors of the second,fourth, and sixth pluralities of transistors; (6) a first phase-out busbar (e.g., the phase-out bus bar 109-1) to connect the first pluralityof transistors to the second plurality of transistors and to provide afirst phase of alternating current, the first phase-out bus barcomprising a portion sealed in the case and respective portionsextending from the case to contact respective transistors of the firstand second pluralities of transistors; (7) a second phase-out bus bar(e.g., the phase-out bus bar 109-2) to connect the third plurality oftransistors to the fourth plurality of transistors and to provide asecond phase of alternating current, the second phase-out bus barcomprising a portion sealed in the case and respective portionsextending from the case to contact respective transistors of the thirdand fourth pluralities of transistors; and (8) a third phase-out bus bar(e.g., the phase-out bus bar 109-3) to connect the fifth plurality oftransistors to the sixth plurality of transistors and to provide a thirdphase of alternating current, the third phase-out bus bar comprising aportion sealed in the case and respective portions extending from thecase to contact respective transistors of the fifth and sixthpluralities of transistors.

Inverter Integration

Attention is now directed to integration of the inverter in thepowertrain of an electric vehicle. In some implementations, an inverter(e.g., the inverter 800, FIGS. 8-13) is housed in the same casting thathouses the electric motor and gearbox. For example, FIGS. 14-16 arerespective side views of a casting 1400. The side view of FIG. 15 isopposite to the side view of FIG. 14. The side view of FIG. 16 resultsfrom rotating the casting 1400 90 degrees in appropriate directions withrespect to the side views of FIGS. 14 and 15. As shown in FIG. 16, thecasting 1400 may include a first portion 1400A and a second portion1400B that are joined (e.g., bolted together) using bosses 1402 duringassembly, to encase components within the casting 1400. The casting 1400may be manufactured by die casting and may be aluminum.

FIG. 17 is a cross-sectional view showing components within the casting1400 in accordance with some implementations. These components includean inverter 1404 (e.g., the inverter 800, FIGS. 8-13), electric motor1406, and gearbox 1416. The inverter 1404 receives DC power from abattery external to the casting 1400 and converts the DC power to ACpower, which is provided to the motor 1406. The motor 1406 includes arotor 1412 inside a stator 1408. The stator 1408 has associated statorwindings 1410, to which the AC power from the inverter 1404 is provided,at both ends. The stator windings 1410 are thus electrically coupled tothe output (e.g., phase-out bus bars) of the inverter 1404; in thismanner, the inverter 1404 is coupled to the motor 1406 to provide the ACpower to the motor 1406. The rotor 1412 includes a rotor shaft 1414 thatextends beyond one end of the stator 1408. The gearbox 1416 includes agear 1418 (FIGS. 18A-18B) on the rotor shaft 1414, intermediate gearing1420, and a final gear 1422 (e.g., a differential gear). Theintermediate gearing 1420 couples the rotor shaft 1414 with the finalgear 1422. The rotor shaft 1414 is situated between the inverter 1404and components of the gearbox 1416, including the intermediate gearing1420 and final gear 1422 but excluding the gear 1418, as shown. Aportion of the intermediate gearing 1420 (e.g., a portion of the gear1424, FIGS. 18A-18B), however, may overlap the rotor shaft 1414, asshown.

FIGS. 18A and 18B are respective side and perspective views ofcomponents within the casting 1400 situated at their positions withinthe casting 1400, but with the casting 1400 omitted for visual clarity,in accordance with some implementations. The gear 1418 is axiallymounted on the rotor shaft 1414 (i.e., the gear 1418 is connected to andconcentric with the rotor shaft 1414). The intermediate gearing 1420(FIG. 17) includes gears 1424 and 1426 mounted axially and spaced aparton a shaft 1421 (i.e., the gears 1424 are connected to, concentric with,and spaced apart on the shaft 1421). The shaft 1421 is situated on aside of the rotor shaft 1414 opposite to the inverter 1404 (i.e., theinverter 1404 is on a first side of the rotor shaft 1414 and the shaft1421 is on a second side of the rotor shaft 1414 opposite to the firstside; these sides may be defined as opposite sides of a plane passingthrough the rotor shaft 1414, such as the plane corresponding to thecenter line of the rotor shaft 1414 shown in FIGS. 18A-18B). The gear1424 engages with the gear 1418 (i.e., teeth of the gear 1424 engagewith teeth of the gear 1418). The gear 1426 engages with the final gear1422 (i.e., teeth of the gear 1426 engage with teeth of the gear 1422).The final gear 1422 may be connected to an axle 1428, such that thegearbox 1416 allows the motor 1406 to rotate the axle 1428 and therebyprovide drive. The axle 1428 is situated on a side of the rotor shaft1414 opposite to the inverter 1404 (i.e., the inverter 1404 is on afirst side of the rotor shaft 1414 and the axle 1428 is on a second sideof the rotor shaft 1414 opposite to the first side; these sides mayagain be defined as opposite sides of a plane passing through the rotorshaft 1414, such as the plane corresponding to the center line of therotor shaft 1414 shown in FIGS. 18A-18B).

In some embodiments, the inverter 1404 (e.g., the inverter 800) includesa case 602 (FIG. 6), transistors 1404 (e.g., transistors 202, 204, 206,210, 212, and 214), and heat sink casing 804 with one or more heat sinks810 (FIGS. 8-10). A capacitor (e.g., capacitor 102) and portions ofphase-out bus bars (e.g., phase-out bus bars 109) are sealed in the case602. The transistors 1404 are thermally coupled to the one or more heatsinks 810 for heat dissipation. The transistors 1404 are situatedbetween the case 602 and the heat sink casing 804, and thus between thecase 602 and the one or more heat sinks 810 (e.g., as shown in FIGS.8-10). The inverter 1404 also includes a battery coupling 812. Thiscompact inverter design, combined with the difference in size betweenthe stator 1408 and rotor shaft 1414, allows the inverter 1404 to fitwithin the casting 1400.

It will also be understood that, although the terms first, second, etc.are, in some instances, used herein to describe various elements, theseelements should not be limited by these terms. These terms are only usedto distinguish one element from another. For example, a first transistorcould be termed a second transistor, and, similarly, a second transistorcould be termed a first transistor, without departing from the scope ofthe various described implementations. The first transistor and thesecond transistor are both transistors, but they are not the sametransistor unless explicitly stated as such.

The terminology used in the description of the various describedimplementations herein is for the purpose of describing particularimplementations only and is not intended to be limiting. As used in thedescription of the various described implementations and the appendedclaims, the singular forms “a”, “an” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will also be understood that the term “and/or” as usedherein refers to and encompasses any and all possible combinations ofone or more of the associated listed items. It will be furtherunderstood that the terms “includes,” “including,” “comprises,” and/or“comprising,” when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof.

As used herein, the term “if” is, optionally, construed to mean “when”or “upon” or “in response to determining” or “in response to detecting”or “in accordance with a determination that,” depending on the context.Similarly, the phrase “if it is determined” or “if [a stated conditionor event] is detected” is, optionally, construed to mean “upondetermining” or “in response to determining” or “upon detecting [thestated condition or event]” or “in response to detecting [the statedcondition or event]” or “in accordance with a determination that [astated condition or event] is detected,” depending on the context.

The foregoing description, for purpose of explanation, has beendescribed with reference to specific implementations. However, theillustrative discussions above are not intended to be exhaustive or tolimit the scope of the claims to the precise forms disclosed. Manymodifications and variations are possible in view of the aboveteachings. The implementations were chosen in order to best explain theprinciples underlying the claims and their practical applications, tothereby enable others skilled in the art to best use the implementationswith various modifications as are suited to the particular usescontemplated.

1. A powertrain for an electric vehicle, comprising: a castingcomprising a first portion and a second portion bolted together; anelectric motor comprising a stator and a rotor housed in the casting,the rotor comprising a rotor shaft extending beyond the stator to form agap between the rotor shaft and the casting; an inverter, housed in thegap between the rotor shaft and the casting and coupled to the electricmotor, to convert direct current from a battery to alternating currentfor the electric motor; and a gearbox housed between the first portionand the second portion of the casting and connected to the electricmotor, wherein: the inverter is situated on a first side of the rotorshaft; and the gearbox is configured to be connected to an axle on asecond side of the rotor shaft, opposite side of the first side. 2.(canceled)
 3. The powertrain of claim 1, wherein the gearbox comprises:a first gear axially mounted on the rotor shaft; intermediate gearingmounted on a shaft to a first side of the rotor shaft and comprising asecond gear and a third gear, the second gear engaging the first gear;and a fourth gear that engages the third gear to provide drive, whereinthe inverter is situated on a second side of the rotor shaft opposite tothe first side.
 4. The powertrain of claim 3, wherein the fourth gear isa differential gear.
 5. The powertrain of claim 1, wherein the invertercomprises: a capacitor sealed in a case; a plurality of phase-out busbars having portions sealed in the case with the capacitor, thephase-out bus bars to provide the alternating current; a plurality oftransistors external to the case and coupled to respective phase-out busbars of the plurality of phase-out bus bars; and one or more heat sinks,wherein the plurality of transistors is thermally coupled to the one ormore heat sinks and is situated between the case and the one or moreheat sinks.
 6. The powertrain of claim 1, wherein the first side, onwhich the inverter is situated, and the second side, on which the axleis located, are opposite sides of a plane passing through the rotorshaft.
 7. An electric vehicle, comprising: an axle; and a powertrain forthe electric vehicle, comprising: a casting comprising a first portionand a second portion bolted together; an electric motor comprising astator and a rotor housed in the casting, the rotor comprising a rotorshaft extending beyond the stator to form a gap between the rotor shaftand the casting; an inverter, housed in the gap between the rotor shaftand the casting and coupled to the electric motor, to convert directcurrent from a battery to alternating current for the electric motor;and a gearbox housed between the first portion and the second portion ofthe casting and connected to the electric motor, wherein: the inverteris situated on a first side of the rotor shaft; and the gearbox isconnected to an axle on a second side of the rotor shaft, opposite sideof the first side.
 8. The electric vehicle of claim 7, wherein thegearbox comprises: a first gear axially mounted on the rotor shaft;intermediate gearing mounted on a shaft to a first side of the rotorshaft and comprising a second gear and a third gear, the second gearengaging the first gear; and a fourth gear that engages the third gearto provide drive, wherein the inverter is situated on a second side ofthe rotor shaft opposite to the first side.
 9. The electric vehicle ofclaim 8, wherein the fourth gear is a differential gear.
 10. Theelectric vehicle of claim 7, wherein the inverter comprises: a capacitorsealed in a case; a plurality of phase-out bus bars having portionssealed in the case with the capacitor, the phase-out bus bars to providethe alternating current; a plurality of transistors external to the caseand coupled to respective phase-out bus bars of the plurality ofphase-out bus bars; and one or more heat sinks, wherein the plurality oftransistors is thermally coupled to the one or more heat sinks and issituated between the case and the one or more heat sinks.
 11. Theelectric vehicle of claim 7, wherein the first side, on which theinverter is situated, and the second side, on which the axle is located,are opposite sides of a plane passing through the rotor shaft.